Struct Event 

pub struct Event {
    pub event_id: Uuid,
    pub aggregate_type: String,
    pub aggregate_id: String,
    pub sequence: i64,
    pub event_type: String,
    pub payload: Value,
    pub audit: AuditMetadata,
    pub timestamp: u64,
}

Core event type representing an immutable domain event.

Fields

• event_id: Unique identifier for this specific event occurrence
• aggregate_type: Type of aggregate this event belongs to (e.g., “User”)
• aggregate_id: ID of the specific aggregate instance
• sequence: Sequential number within the aggregate stream (starts at 1)
• event_type: Type of event (e.g., “UserRegistered”)
• payload: Event data as JSON (flexible, evolvable schema)
• audit: HIPAA audit metadata. pending() until the bus stamps it.
• timestamp: When the event occurred (milliseconds since UNIX epoch)

Fields

event_id: Uuid

Unique identifier for this event

aggregate_type: String

Aggregate type (e.g., “User”, “Order”)

aggregate_id: String

Aggregate instance identifier

sequence: i64

Sequence number within the aggregate (starts at 1)

event_type: String

Event type (e.g., “UserCreated”, “ProfileUpdated”) Convention: Past tense, PascalCase

payload: Value

Event payload as JSON

audit: AuditMetadata

HIPAA audit metadata. AuditMetadata::pending() until the CommandBus overwrites it before append. EventStore::append implementations call audit.validate() and reject pending values.

timestamp: u64

Wall-clock timestamp (milliseconds since UNIX epoch). For HIPAA audit-quality time, use audit.timestamp_utc_us (microsecond precision).

Implementations

impl Event

pub fn new( aggregate_type: impl Into<String>, aggregate_id: impl Into<String>, sequence: i64, event_type: impl Into<String>, payload: Value, ) -> Self

Create a new event with audit = AuditMetadata::pending().

Aggregates call this from handle() and the CommandBus overwrites the audit field with a request-scoped value before persisting. The pending placeholder fails store-side validation, so a forgotten stamp is impossible to commit.

Example

use arc_core::event::Event;
use serde_json::json;

let event = Event::new(
    "User",
    "user-456",
    1,
    "UserCreated",
    json!({ "name": "Bob", "email": "bob@example.com" }),
);
assert!(event.audit.is_pending());

pub fn with_audit(self, audit: AuditMetadata) -> Self

Replace audit with a fully-stamped value. Used by CommandBus before calling EventStore::append.

pub fn to_json(&self) -> Result<String, Error>

Serialize event to JSON string.

pub fn from_json(json_str: &str) -> Result<Self, Error>

Deserialize event from JSON string.

Trait Implementations

impl Clone for Event

fn clone(&self) -> Event

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Event

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for Event

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl PartialEq for Event

fn eq(&self, other: &Event) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Serialize for Event

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for Event